Gregory Stark wrote: > > Ron Mayer <[EMAIL PROTECTED]> writes: > > > For example, on our sites hosted with Amazon's compute cloud (a great > > place to host web sites), I know nothing about spindles, but know > > about Amazon Elastic Block Store[2]'s and Instance Store's[1]. I > > have some specs and are able to run benchmarks on them; but couldn't > > guess how many spindles my X% of the N-disk device that corresponds > > to. > > Well I don't see how you're going to guess how much prefetching is optimal for > those environments either... > > > For another example, some of our salesguys with SSD drives > > have 0 spindles on their demo machines. > > Sounds to me like you're finding it pretty intuitive. Actually you would want > "1" because it can handle one request at a time. Actually if you have a > multipath array I imagine you would want to think of each interface as a > spindle because that's the bottleneck and you'll want to keep all the > interfaces busy.
I assume everyone would want at least one because you would want the page to be prefetched while you are processing the existing page. I think a larger problem is that it is likely the page prefetch will take longer than processing the existing page, which might mean that you need to prefetch a few pages ahead to allow read reordering for better performance. -- Bruce Momjian <[EMAIL PROTECTED]> http://momjian.us EnterpriseDB http://enterprisedb.com + If your life is a hard drive, Christ can be your backup. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers